Properties, performance and practical interest of the widely linear MMSE beamformer for nonrectilinear signals
Properties, performance and practical interest of the widely linear MMSE beamformer for nonrectilinear signals
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DOI：
10.1016/j.sigpro.2013.09.017
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发表时间：
2014-04
期刊：
影响因子：
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通讯作者：
P. Chevalier;J. Delmas;A. Oukaci
中科院分区：
文献类型：
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作者：
P. Chevalier;J. Delmas;A. Oukaci
近 20 年来，二阶 (SO) 非圆形信号的宽线性 (WL) 最小均方误差 (MMSE) 估计引起了人们的极大兴趣。在无线电通信网络的背景下，已经特别表明WL MMSE接收器允许实现一种直线干扰的单天线干扰消除(SAIC)，例如二进制相移键控(BPSK)或幅移键控(ASK)干扰，或准直线干扰，例如最小频移键控(MSK)、高斯MSK(GMSK)或偏移正交幅度调制(OQAM) 干扰，因此他们对全球移动通信系统 (GSM) 蜂窝网络特别感兴趣。然而，人们可能想知道 WL MMSE 接收器对于 SO 非圆形非直线干扰是否仍然有吸引力，而在实践中并不那么稀缺。本文的目的主要是通过以独立且统一的方式对 WL MMSE 波束形成器在存在任意非圆形信号和不一定是直线的干扰的情况下的行为、属性和性能给出一些新的见解来回答这个重要问题。尤其令人惊讶的是，WL MMSE 接收机对非直线的强干扰失去了实际兴趣。因此，这一突破产生了一个新的开放问题，即在给定的噪声观测中，线性接收器和 WL MMSE 接收器之间的选择对应于直线性（和/或准直线性）而不是非圆性的检测。虽然这个问题超出了本文的范围，但我们最终提出了基于盲源分离方法的初步工具来解决这个问题。
Widely Linear (WL) Minimum Mean Square Error (MMSE) estimation has received a great interest these last 20 years for second order (SO) noncircular signals. In the context of radio communications networks, it has been shown in particular that WL MMSE receivers allow to implement Single Antenna Interference Cancellation (SAIC) of one rectilinear interference, such as Binary Phase Shift Keying (BPSK) or Amplitude Shift Keying (ASK) interference, or of quasi-rectilinear interference, such as Minimum Shift keying (MSK), Gaussian MSK (GMSK) or Offset Quadrature Amplitude Modulation (OQAM) interference, hence their great interest for Global System for Mobile Communications (GSM) cellular networks in particular. However, one may wonder whether WL MMSE receivers remain attractive for SO noncircular nonrectilinear interferences, not so scarce in practice. The purpose of this paper is mainly to answer to this important question by giving, in a self-contained and unified way, some new insights into the behavior, properties and performance of the WL MMSE beamformer in the presence of arbitrary noncircular signals and interference which are not necessarily rectilinear. It is shown in particular that, surprisingly, WL MMSE receivers lose their practical interest for strong interferences which are not rectilinear. This breakthrough thus generates a new open problem for the choice between linear and WL MMSE receiver corresponding to the detection of rectilinearity (and/or quasi-rectilinearity), instead of noncircularity, in a given noisy observation. Although this question is out of the scope of this paper, we finally propose preliminary tools based on blind source separation methods to solve this problem.